Tracking in CMS: software framework and tracker performance

Tracking in LHC experiments requires reconstruction software that is able to deal with high hit multiplicity and complex detector geometry. The software framework should also be flexible enough to allow online event reconstruction and selection at high trigger levels. We present an object-oriented framework that fulfills these constraints. We describe two track reconstruction algorithms currently implemented within this framework, with a comparison of their performance at high multiplicity of noise hits. We present the performance of the CMS tracker in terms of momentum and impact parameter resolutions, evaluated by means of simulation studies.